In the operation of certain types of electrolytic cells, including fuel cells, it is advantageous to balance the pressure between a gas and a liquid within the pores of a porous gas electrode. By balancing the pressure between gas and liquid, the contact between gas and liquid is restricted to within the pores of the electrode where a three phase reaction between the electrolyte, the gas, and the electrode can take place.
In the operation of electrolytic cells with vertically positioned gas electrodes, a problem exists in balancing the pressure of a gas with a liquid electrolyte. As is true of any liquid, the pressure exerted by the electrolyte against the containing surface of the cell increases as the depth of the liquid increases. In the case of a vertically positioned gas electrode, this liquid head pressure is exerted on the porous electrode and increases with increasing depth of the electrolyte.
In the operation of an industrial-size vertical electrode, the required balance of pressure between the liquid electrolyte and gas within the pores of the electrode generally takes place along the center section of the electrode. Gas sometimes escapes through the porous electrode by "bubbling out" at the top of the electrode, where the resisting head pressure of the liquid electrolyte is slight. Similarly, at the bottom of the electrode, the head pressure of the liquid is usually greater than the pressure of the gas, sometimes causing the electrode to flood in its lower sections.
The "bubbling out" of gas at the top of the electrode, and the flooding at the bottom of the electrode, both result in inefficient cell operation. It is, therefore, a general object of the present invention to provide a system for balancing a gas with a liquid electrolyte within the pores of an industrial sized, vertical gas electrode along the electrode's entire vertical length.